This project will compare the degree, mechanisms, and processes of control over heroin use across three sample groups of regular and current users: controlled, marginals, and addicts-not-in-treatment. These groups (quantitatively defined according to amount, intervals between, recency, and stability of prior use) represent a spectrum of heroin-using styles ranging from moderate, occasional, i.e., controlled use, to daily, physiologically addictive use. Control will be evaluated within and across these groups according to frequency, stability, and other variables. Longitudinal data on 120 subjects will be collected by the research team and by indigenous data gatherers through three depth interviews with each subject at one-year intervals. Data will be validated through interviews with at least one friend for each subject. Analysis will emphasize the relation between setting variables (the characteristics of the physical and social environments in which heroin is used) and control (especially how one using style evolves into another). Data on these large and relatively unstudied groups will be used to formulate hypotheses with practical implications. Findings would assist treatment personnel in sorting between and tailoring approaches to different clients and would provide prognostic indicators. Typologies of use and differentiating measures will be developed which could be adapted economically to epidemiological research, and which will be field-tested by a local survey in the fourth year of this project. Findings might also: 1) suggest new treatment alternatives based on enhancing clients' control rather than exclusively promoting abstinence; 2) indicate how public policy and education could become more responsive to the full range of drug takers; and 3) provide new insights into the interaction between psychological and socio-structural variables in various drug-using patterns.